feat(desktop): embed BoosAPI Desktop client as a subproject

Vendor the rebranded BoosAPI Desktop client (Tauri + Vue) into metapi as
a monorepo subdirectory under desktop/. Source only — node_modules,
dist, Cargo target and the upstream .git history are excluded.

desktop/ keeps its own independent Cargo workspace (desktop/src-tauri
with crates/*); it is not part of the backend boosapi crate, so a
`cargo check` at the metapi root still compiles only the backend. Build
the desktop app from desktop/src-tauri per desktop/README.md.

Note: app icons are still placeholder assets pending the final BoosAPI
logo. The updater signing keys live outside the repo and are not
included.

desktop/libs/markstream-vue/playground-react18/netlify.toml

@@ -0,0 +1,12 @@
+[build]
+publish = "dist"
+command = "npx pnpm i && pnpm --filter stream-markdown-parser build && pnpm --filter markstream-react build && npm run build"
+
+[build.environment]
+NPM_FLAGS = "--version"
+NODE_VERSION = "22"
+
+[[redirects]]
+from = "/*"
+to = "/index.html"
+status = 200